题干

下列有关生物实验的描述,正确的是(   )

A:“观察藓类叶片细胞的叶绿体形态分布”与“植物根尖细胞的有丝分裂”,两实验过程中都要使实验材料保持活性

B:对酵母菌计数时,用吸管吸取培养液滴满血球计数板的计数室及其四周边缘,盖上盖玻片后即可镜检

C:紫色洋葱鳞片叶表皮细胞可用于观察质壁分离,但不能用于观察染色体

D:用两种不同浓度的2,4﹣D溶液分别处理月季插条形态学下端,观察并比较扦插后插条的生根条数会发现,低浓度2,4﹣D处理的插条生根数多

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C

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阅读下列短文,从每题所给的四个选项(A, B, C和D)中.选出最佳选项.

    What's your opinion on spicy food? Some people cannot handle even the smallest amount of chili(辣椒) in their dinner while others can't get enough of it.       

Scientists have long been puzzled by why some people love chili and others loathe it. Plenty of research has been done on the subject, dating back to as far as the 1970s. Previous results showed that a love of chili is related to childhood experiences, and cultural influences affect our taste buds, too. But the latest study has found that a person's love of spicy food may be linked to his or her personality more than anything else, CBC News reported.

     “We have always assumed that liking drives intake---we eat what we like and we like what we eat. But no one has actually directly bothered to connect these personality traits with intake of chili peppers,” said Professor John Hayes from Pennsylvania State University, who led the study.       

But before you look at the study, you should first know that “spicy” is not a taste, unlike sour, sweet, bitter and salty. It is, in fact, a burning sensation that you feel on the surface of your tongue. This got scientists thinking that maybe a love of spicy food is brought about by people's longing for thrill, something they usually get from watching action movies or riding a roller coaster.

In the study, 97 participants, both male and female, were asked to fill out questionnaires about certain traits of their personality, for example. Whether they like new experiences or tend to avoid risks. They were then given cups of water with capsaicin(辣椒素), the plant chemical that makes chili burn, mixed into them.

By comparing the answers to questionnaires and what participants said they felt about the spicy water. Researchers found that those who most tended to enjoy action movies or take risks were about six times more likely to enjoy the spicy water.

    Interestingly, we used to believe that the reason some people can withstand spicy food is that their tongue have become less sensitive to it. However, this latest study has found otherwise. It's not that it doesn't burn as badly, it's that you actually learn to like the burn,” Hayes explained.